1. Reflection
Physics Chapter 18a

2. Law of Reflection
Angle of incidence equals angle of reflection

3. Reflection Change in direction of wave at interface between two media
Reflecting surface smoothness controls type of reflection
Specular: smooth surface, forms good image
Diffuse: rough surface, does not form good image

4. Reflections

5. Example The angle of incidence of a light ray is 42o. What are:
The angle of reflection
The angle the incident ray makes with the mirror
The angle between the incident ray and the reflected ray

6. Plane Mirror Flat mirror
Forms a virtual image at the same distance that the object is
Virtual image is upright
Mirror equation: 1/p + 1/q = 1/f
p=object distance
q=image distance
f=focal length

7. Plane Mirror

8. Concave Mirror Concave mirror is curved away from observer
Mirror reference points:
Optical axis
Normal at center of mirror
Also called principal axis
Focal point
Point on optical axis where every reflected ray passes through
Focal length: distance from mirror to focal point (along optical axis)

9. Concave Mirrors Reflections:
Rays parallel to principal axis reflect through focal point
Rays through focal point reflect parallel to principal axis
Rays through center (along principal axis) reflect back along same path

11. How do we find where an image is?
Draw carefully!!

12. How do we find where an image is?
Draw carefully!!

13. How do we find where an image is?
Draw carefully!!